Electrolytic condenser combined with autotransformer.



E. E. E. CREiififHTON: ELEOTROLYTIG CONDENSER COMBINED WITH AUTOTRANSFORMER. APPLICATION FILED JULY 13, 1907.

933,697. Patented Sept. 7, 1909.

2 SHEETS-SHEET 1.

Fig.1

I I l 3 I I I3 (9 e e 14523155555 I .ZNYLNTUH m gm I'LMEH E12? EHEIGHTUM AT TY E. E. P. GREIGHTON. ELECTROLYTIC CONDENSER COMBINED WITH AUTOTRANSFORMER. APPLICATION FILED JULY 13, 1907.

933,697, Patented Sept. '7, 1909.

Z SHEETS-SHBET 2.

K622755555.- ivy/ENTER ATT'YT UNITED STATES PATENT ornron.

ELMER E. F. CREIGHTON, OF SCI-IENECTADY, NEW YORK, ASSIGNOR T0. GENERAL ELEC- TRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTROLYTIC CONDENSER COMBINED WITH AUTOTRANSFORMER.

To all whom it may concern:

Be it known that LELME E, F. CREIGH- row, a citizen of the United States, residing at Schenectady, county of Schenectady, State of. New York, have invented certain new and useful Improvements in Electrolytic Condensers Combined-with Autotransformers, of which the following is a specification.

This invention relates to the use of aluminum electrolytic condensers and comprises an arrangement of apparatus including a plurality of condenser cells and an imapplication, Serial No. 325,195, to use a plu trodes immersed-in a suitable electrolyte and rality of cells containing aluminum elecconnected in series. The current-limiting efieet of this device is due to the thin film of aluminum oXid or hydroxid which forms on each plate when current flows through the cell. The resistance. of the film is, however, limited to a certain critical voltage, and if this is. exceeded the film valves open and permit the current of the excessive potential to flow freely. Upon a reduction of the voltage to a value below the critical voltage, the film valves again close and choke back the current. By connecting a number of such cells inseries, the total critical voltage of the device can be made sufficiently high to control any given line voltages.

' \Vhenan electrolytic condenser of this type is permanently in circuit between line and ground, there is a small leakage current which keeps thefilm formed and ready for action. After being in service for some time, however, there is a tendency for the cells to become unbalanced to the extent that one or more cells will cease to do their full share of the work. and will thereby increase the strain on the remaining cells. This overloading of the remaining cells may result in further break downs until the effectiveness of the device as a lightning arrester is destroyed. In other words, a series of simple aluminum cells connected permanently in circuit cannot be trusted to maintain among the several cells a uniformand equal d1str1- Specification of Letters Patent. Patented Sppt, 7 1 909 Application filed .Tu1y13, 1907.

Serial N0. 383,637.

bution of the potential. I have found that if each cell is shunted by an impedance of proper value, the'cells will continue to operate in series for an indefinite time. The impedance may be a transformer winding having its coils or sections connected at intervalsto' the cells of the condenser and preferably in such a way that each cell is shunted by the same amount of impedance or reactance.

The accompanying drawing illustrates modes of carrying out my invention.

Figure 1 shows a six-cell condenser connected with an autotransfonner; Fig 2- shows a bank of three sets of such cells 7o connected in series; and Fig. 3 shows a similar installation with equalizing coils connecting the transformers.

The cells consist of glass jars l partly filled with electrolyte above which is a layer of oil to prevent evaporation. The electrodes 2 are aluminum plates; those in ad jacent jars being connected in pairs by connectors 3. The end plates in the series are connected to the lines laof a transmission system, and the middleplates are grounded at 5.

The autotransformer has a core 6, which is preferably a closed magnetic circuit on which is wound the coil 7 divided intoportions preferably equal which are connected to the plates 2 in the cells, so as to be in shunt thereto.

In operation, whenever one cell becomes abnormal, there isa transference of energ 7 from the other coils of the transformer which tends to equalize the potential. The resistance of a cell depends upon the electrolyte, the thickness of the films on the platesgand other conditions, and -the film may increase in thickness, or electrolytic action may eliminate impurities from the electrolyte or from the film, in which case the resistance rises and if constant current is maintained through the cell the difference 1 of potential between the electrodes becomes greater? than normal. On the other hand, for eziample, the film may break down in one spot, there maybe an impurity in the plate, or the electrolyte may become impure, in which case the resistance of the cell becomes less than normal and.the same potential on the electrodes causes more current to flow, or if the normal current is maintained the difference of potential between the electrodes becomes less. The auto-transformer .shown in the drawings is connected across the line and if, for example, the resistance of a cell decreases and consequently the po-: tential between the two electrodes tends to decrease, the transformer winding connected to those electrodes at once begins to furnish energy suflicient to maintain practically the paratively little energy transfer to main-.

sistance of the cell is belownormal.

normal difference of potential between the electrodes, in spite of the fact that the re- Since the cells are all identical, it requires comtain almost-equal voltage across the cells. In case-the installation is a large one, it may be divided into sections 8, 9, 10, as shown in Fig. 2, each .with its own autotransformer. Any number ,may be used, the drawing showing three for convenience, merely. The sections are connected in series between line and linefor line and ground,' and the voltage of one section cannot exceed that of the others, because'of theself -regulating eflect of the connected coils.

In Fig. 3 is shown a further modification,

in which the sections are tied together electrically by the equalizin coils 11, 12, 13, 14, the first on the core of section 8, the

'- neXt two on the core of section 9,' and the last on the core of section 10. Coils 11 and 12 are connected in series, andso are coils 13 and 14, and they tend to maintain a uni form flux in all the cores, and thus keep the voltage of all the cells approximately equal. Fig. 4 shows an equivalent means for maintaining the cells at equal voltage; In-

stead of an autotransformer, a resistance 15 is shunted across each cell. In this. case, if the potential of a cell rises, the resistance in parallel therewith takes more current and tends to equalize. In this construction there is a continuous loss of energy through the resistances, but the firstcost is less than that of an autot-ransformer.

hat I claim as new',-and-desire to secure by Letters Patent of the United States, is,

1'. The combination withan electrolytic condenser, comprising a plurality of cells, of

5.. The combination with an electrolytic.

condenser comprising a plurality of cells, ofan autotransformer having its con divided into portions, each in shunt to one of said cells.

6. The combination with an electrolytic condenser comprising a plurality of cells, of an autotransformer havingits coils divided into equal portions the same in number as said cells, each portion being shunted across its respective cell.

17. The combination with an electrolytic condenser comprising a plurality of cellsdivided into sections connected iii-series, of an autotransformer for each section, having its coil divided into portions each in shunt to a cell. I

8. The combination with an electrolytic condensercomprising a plurality of cells divided into sections connected'in series, of an autotransformer for each section with portions of its coil in shunt to said cells, and meansfor equalizing the magnetic flux in all of said autotransforniers. 9. The combination with an electrolytic condenser comprising a plurality of cells, of

an autotransformer having its coil divided into portions,.each in shunt to one of said cells, and electrically-connected coils on the cores of said autotransformers.

10. The combination of a transformer windingand a plurality of aluminum condenser cells. each in shunt with a portion of said winding.

11. The combination of an inductive 'device and a plurality of aluminum'cells each in shunt with a portion of said device.v 4 r 12. The combination of a reactance coil and a plurality of aluminum condenser cells shunting equal portions ofthe] winding thereof. I

13. Thecombination with transformer;

windings, of a plurality 'of aluminumpcondenser cells shunting portions of said windings and means for equalizing the magnetic flux in the shunted portions of said windings.

14. The combinationwith an auto-transformer comprising a plurality of windings,

of aplurality of aluminum cells each in shunt with a portion of said windings and duct-ive relation to said windings for equalizing the magnetic fiuxthrough said windings.

windings, of a plurality of aluminum con 15. The combination with transformerelectrically connected coils mounted in in- 3 denser cells each in shunt with a portion of I said windings and coils mounted in inductive relation to said windings, said coils being interconnected to control the magnetic flux in said windings.

In witness whereof, I have hereunto set my hand this 12th day of July,1907.

ELMER E. F. CREIGHTON.

Witnesses:

BENJAMIN B. HULL, HELEN- ORFoRD. 

